| Songyuan is located in the midwest of Jilin province, belongs to the songnenplain hinterland, groundwater is an important water source of Songyuan water supply.In recent years, the shortage of groundwater resources, deterioration of groundwaterwater quality and other issues had seriously restricted the development of socialeconomy and the improvement of people’s living standards. Therefore, to solve theproblem of regional groundwater, the characteristics and evolution trend ofgroundwater must be understanded and carry on the effective development andutilization, this’s significative to guarantee social stability and sustainable economicdevelopment of Songyuan.The quaternary system aquifer is widely distributed with rich water andappropriate buring depth, different causative rickle of quaternary system constitutesthe aquifer with larger using value and higher importance than tertiary and cretaceoussystem. Groundwater flows to the northern zone from the southeast of the study area,the water level difference is about100m, there is obvious watershed appearing inHeJian plot.The primary target aquifer of groundwater resource evaluation is quaternary poreaquifer including the pore water and pore confined water. Evaluating groundwaterresource of Songyuan by analytic method and water amount equilibrium method,theresults showed that the average amount of groundwater recharge was12.73108m3/a,exploitable groundwater was12.73108m3/a in the study area from2002to2012;55water sample of unconfined wells and42of confined wells were analyzed, resultsshowed that hydrochemical type of unconfined water in central and northern ofresearch area were mainly HCO3-Ca and HCO3-Mg, the southern was mainlyCl-SO4-Mg; hydrochemical type of confined water was HCO3-Ca-Mg in Hejian plot,HCO3-Na and HCO3-Ca in central low plain and HCO3-Na-Mg in the south. Thegroundwater quality was mainly Ⅳ class, Ⅴ class water distributed sporadically instudy area.Quantity, quality of groundwater numerical model was established, the evolutiontrend of water level and the "TN" were predicted.Prediction results showed that the groundwater was in state of negative balance under the present situation of miningand underground water level continued to decline. Using three different solutions topredict groundwater level, results showed that the water level change were greatlyinfluenced by production, when the growth of exploitation quantity changedaccording to the past trend, unconfined groundwater level declined about2~6m,confined groundwater level declined about3~6m.Numerical model of groundwaterquality forecast suggested that concentration of―TN―in the groundwater showed atrend of slow increase year by year, enrichment was also obvious in some special area.Establishing the fuzzy comprehensive evaluation model to analyze the evolutiontrend of the groundwater system in the study area combining partition of groundwaterresources calculation,the evaluation time period was2002~2018.Selecting11evaluation factors and each of them was divided into five level respectively toquantify the index procedure, then calculated through formula of membership gradefunction and combined with the results of the model, finally made analysis andevaluation of the evolution trend of the groundwater water quantity, water qualitysystem in the study area. Evaluation results showed that the groundwater system inthe "good" areas were mainly distributed in low plain area in the Midwest and thesecond Songhua river and the Lalin river basin, the "bad" areas were mainlydistributed in loose Hejian plot.With the passage of time, the "good" area decreased inthe central low plain, especially near the Loose Hejian plot.In the evaluation period,2calculate partition were evolved to the "good" direction of the groundwater system,10kept "Essentially unchanged" mainly distributed in loose Hejian plot and the Midwestof low plain,12to the―bad‖direction mainly distributed in southwest area of the lowplain and loose Hejian plot adjacent to the west of the low plain. |
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